Motörhead are one of those bands, like ZZ Top or AC/DC, that seemingly everyone who likes loud electric guitars can agree on. They exist for one reason: speed. No, seriously — bassist/vocalist Ian “Lemmy” Kilmister formed Motörhead (originally Bastard) after being kicked out of space-boogie overlords Hawkwind for being into meth, rather than the hallucinogenics his bandmates favored. He was busted at the Canadian border on tour, and that was it; he was out, and Hawkwind’s glory era pretty much came to an end with his departure.

Lemmy wasted no time getting his next project rolling; Motörhead’s first recording sessions were in 1975, though they weren’t released until 1979, after the band had switched labels and achieved some success. Their true debut came in 1977, at the peak of punk rock, and Motörhead were immediately accepted by both the punks and the headbangers, something that’s remained true to this day. (Lemmy claims he used to see Johnny Rotten hanging around Hawkwind gigs, proving that artistic boundaries are often more porous than they’re credited as being.)

Musically, they arrived fully formed, with a sound that hasn’t changed much at all in four decades. Motörhead songs are fast, aggressive, and primitive in the best rock ‘n’ roll style. But Lemmy’s lyrics are sharp, witty, and cutting, taking on sex, war, and religion with little thought for the feelings of the overly sensitive.

There are two major “periods” in Motörhead’s existence: the so-called “classic lineup” of Lemmy, guitarist Fast Eddie Clarke, and drummer Philthy Animal Taylor (this is the version that made the albums Overkill, Bomber, Ace Of Spades, Iron Fist and the live No Sleep ‘Til Hammersmith), and the current incarnation of Lemmy, guitarist Phil Campbell, and drummer Mikkey Dee, who have been together (plus second guitarist Wurzel, who left in 1995 and died in 2011) since 1992 and have made 12 albums to date. In between, there were a slew of lineup shifts from record to record, but the stability of the last 22 years has been great for the band.

There were definitely some difficult years — commercially and creatively — in the middle, for sure. From the time they left Bronze Records in 1984 to roughly 2001, Motörhead were bouncing from label to label, losing and gaining members, working with producers who didn’t suit them (Bill Laswell) and making ill-advised attempts to go commercial. But over the last decade and a half, they’ve made one of the strongest late-career creative comebacks of any band, ever. Motörhead are as good now as they’ve ever been, and frequently better.

The big question at this point is, how much longer can it last? Lemmy’s suffered from diabetes for years, and until very recently refused to change his habits — most notably, his love of cigarettes, and Jack & Coke — to accommodate his health problems. As a result, he had a heart defibrillator implanted in 2013, and was forced to cancel some European concerts after developing a hematoma. He walks with a cane offstage, and just last night, he ended a show in Austin after only three songs. This has become an alarming pattern — last week, he left the stage in Salt Lake City after four songs (and cancelled the following night’s Denver performance) due to altitude sickness — he couldn’t breathe at that height. He’ll turn 70 at the end of 2015, and if this is the end of the line for Motörhead, well, it’s been a hell of a run.